The present invention relates to an apparatus and method for the measuring and dispensing of liquids and, more particularly, to an apparatus and method for the measuring and dispensing of liquid chemicals and agrichemicals in particular.
Liquid agrichemicals such as herbicides, fertilizers, pesticides, fungicides, and the like, are advantageous over solid agrichemicals in many applications. For example, liquid agrichemicals provide faster response, especially in dry conditions, and for pesticides provide more effective control of soil insects.
Regarding certain agrichemicals, government regulations specify that such agrichemicals must be handled with a transfer system that substantially eliminates the possibility of spillage during the transfer of the agrichemical from the supply tank to the holding tank of a sprayer system.
Most modern agrichemicals are sold in a concentrated form which makes them unsuitable for direct application on the crop or field. Consequently, the concentrated agrichemical must be first diluted before application. In order to achieve a proper dilution ratio of the concentrated agrichemical to a diluent, the diluent being generally water, the concentrated agrichemical must be measured before mixing. Depending on various factors such as total end volume of mixture desired which, may be based on application or flow rate and the total acreage to be covered, as well as mixture strengths for various field conditions, etc. the proper mixture ratio is determined. The agrichemical must be accurately measured in order to achieve the proper mixture ratio in order for the agrichemical to properly perform.
Such concentrated agrichemicals generally pose a health hazard upon exposure, and thus, great care should be taken to avoid unnecessary contact therewith. The process of measuring and mixing the agrichemicals can pose a challenge to avoid unnecessary exposure.
Heretofore, various systems for measuring and diluting agrichemicals have generally included a conventional pump disposed in-line with the agrichemical for pumping the agrichemical to a mixing tank or otherwise. Usually a separate in-line pump is also used for pumping the water (diluent) into the mixing tank. Complicated valving is then utilized to control the flow. Unfortunately, such in-line agrichemical pumps tend to corrode very quickly due to the corrosive nature of agrichemicals.
U.S. Pat. No. 5,199,472 (Rollison) discloses a chemical transfer system which does not utilize an in-line pump for transferring the agrichemical from a storage tank to a mixing tank. A metering container assembly receives liquid agrichemical from a storage tank and transfers a desired amount of liquid agrichemical to a mixing tank or the like, without the use of an in-line pump. Referring to FIGS. 3 and 4, a single head air compressor has an inlet and an outlet which may be alternately disposed in fluid communication with the interior of the container or the ambient environment. Utilizing a first three-way valve connected to the inlet of the compressor, and a second three-way valve connected to the outlet of the compressor, the interior of the container may be connected to either the inlet or the outlet of the single head air compressor. When the inlet line of the single head air compressor is connected to the interior of the tank, a suction pressure is created within the interior of the tank which draws liquid agrichemical from a storage tank into the metering container assembly. Contrarily, when the outlet to the air compressor is connected to the interior of the metering container assembly, the liquid agrichemical is expelled from the metering container assembly to a mixing tank or the like. During a filling operation, a user visually observes the level of the liquid agrichemical within the metering container assembly and actuates the valve accordingly when the liquid agrichemical reaches a desired level. In the event a user inadvertently fails to actuate the valves and thereby cease application of suction pressure to the interior of the container, a float assembly disposed at the top of the interior of the container closes the line extending from the exterior of the tank to the inlet of the compressor. In the absence of such a float assembly, the liquid agrichemical would reach the top of the interior of the tank and may be drawn out through the tank line extending to the compressor because of the suction created within the tank line.
For proper operation of the metering container assembly, Rollison discloses a leveling device which is utilized for positioning the metering container assembly in a true vertical position. Such leveling is necessary to provide a proper visual indication to a user of the amount of fluid contained within the metering container assembly by viewing a sight gage, and also to ensure proper operation of an overflow valve. To effect leveling of the metering container assembly, a handle of a leveling means is rotated and a ball float of an indicator is aligned with cross hairs.
Another kind of measuring and dispensing method and apparatus includes a method and apparatus for drawing and measuring an amount of liquid agrichemical and dispensing the measured amount of agrichemical for mixture with water and eventual application onto a field, such as shown in U.S. Pat. No. 5,450,88, assigned to the assignee of the present application, which is hereby incorporated by reference. U.S. Pat. No. 5,450,881 discloses the agrichemical being drawn into a measuring vessel by suction pressure created in one embodiment by an air compressor and valving system, and in another embodiment by a valve pump in conjunction with a three-way valve. The agrichemical is then dispensed from the measuring vessel either by positive pressure created by the same air compressor/valving system, or by suction pressure created by the valve pump/three-way valve. The valve-pump provides both a mixing chamber for the agrichemical and water prior to tank storage for eventual application and controllable suction pressure for drawing the agrichemical out of the measuring vessel for mixing. The valve-pump is also self-cleaning thereby reducing the possibility of cross-contamination.
An object of the present invention is to provide an economical hand-powered agrichemical measuring and mixing system which overcomes the problems of the prior art by having a closed measuring and diluting system, and which does not require venting of the measuring system upon drawing a desired volume therein.
It is another object of the present invention to eliminate the conventional in-line pump.